Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
thuc dan » thuc hanh, hoc dan, thuc vat
ky lang » ky dang, ky tang, tay lang
hieu va » lieu va, hieu qua
dan dan » dang dan, ban dan, dao dan
chu tre » cho tre, chu tri, cuu tre
dan va » doan va, dan ca, ban va
va chu » va che, va cau, va chi
va am » va lam, va cam

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ((ky lang) OR (ky nang)) xa hoi. hieu va am thuc dan dan va chu tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ((ky lang) OR (ky nang)) xa hoi. hieu va am thuc dan dan va chu tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ((ky lang) OR (ky nang)) xa hoi. hieu va am thuc dan dan va chu tre*.